How many CPU cores does Blender support and make sense?
The more, the better in most cases, but you do need to be aware of single thread performance as well. If you get a processor with lots of cores that has very poor single thread performance and use it for work, you might struggle with some operations that cannot use all of the cores. Generally physics simulations tend to use multiple cores a bit less efficiently because they tend to need the results of previous calculations in order to continue so the calculations are difficult to do in parallel. Some other every day modelling tasks also suffer from this. For rendering - the more cores you have, the better, unless you render loads of really fast frames(seconds) in which case preparing the scene for rendering might take more time than actually rendering and during the preparation there are some things done with single thread only - in that case it might be slow.